Bypass turbofan engines produce two exhaust flows, a core engine flow and a fan flow. The core engine flow is discharged from a core flow nozzle after passing through a core engine. The fan flow passes through an annular passageway formed by a nacelle surrounding the core engine and fan duct. The cross-sectional areas through which these two flows pass may be optimized for specific operating conditions, such as take-off, climb, cruise, etc. Variable area fan nozzles that include movable petals are used to enlarge or reduce the nozzle area of the fan flow, and thereby, decrease or increase the exhaust velocity, respectively.